Acceleration of carburization and melting of reduced iron in iron ore-carbon composite using different types of carbonaceous materials

In the ironmaking process, not only faster reduction of iron ore but also the acceleration of carburizing and melting of reduced iron is very important to save energy. In this study, the use of different types of carbonaceous materials having the superior functions for reducing and carburizing is suggested for the acceleration of carburization and melting of reduced iron in a iron ore-carbon composite. A tablet sample made of mixed powder of iron ore and carbonaceous materials such as coal, charcoal, coke, and graphite was heated up to 1 573 K, and its reduction, carburization, and melting behaviors were evaluated. It was found that coal and charcoal, which generate reducing gases at lower temperature, are suitable for the reducing agents. On the other hand, graphite and coke should be used as carburizing agents because of their lower reactivity with CO2. Using coal and graphite for the reducing and carburizing agents, respectively, accelerates the carburization and melting of reduced iron in the composite unlike when only coal is used. The effect of the particle size of graphite on the carburization is strong. Carbon concentration in the reduced iron in the composite held at 1 573 K for 1.8 ks increases with increasing particle size of graphite. Reduction of iron ore is accelerated by mix-grinding of the ore and reducing agent. The carburization is accelerated using charcoal as the reducing agent, whereas agglomeration of melted iron in the mixed grinding sample is inhibited when the reducing agent comprises coal and graphite.